FEAST Dynamic Radar Conflict Management 2 — Questions and Answers
Question 1: Two aircraft are converging at FL290 with a projected closest point of approach (CPA) of 3 NM lateral and 0 ft vertical in 4 minutes. The ICAO minimum radar separation standard in European airspace is 5 NM. The controller should:
- Issue an immediate heading change or level change to one or both aircraft to restore 5 NM separation before the CPA (Correct answer)
- Wait until the aircraft reach 5 NM to see if they maintain own separation
- Instruct both aircraft to increase speed to pass each other more quickly
- Accept 3 NM if TCAS resolution advisory has not been issued yet
Correct answer: Issue an immediate heading change or level change to one or both aircraft to restore 5 NM separation before the CPA
At 4 minutes to CPA with only 3 NM projected separation, the controller must act immediately — the minimum is 5 NM and the situation is trending toward infringement.
Radar separation standards in European en-route airspace are 5 NM lateral or 1,000 ft vertical. When both projected lateral and vertical separation are below the minimum simultaneously, an infringement is imminent. With 4 minutes to CPA, there is time to resolve the conflict safely, but delay reduces options. A heading change or level change for one or both aircraft is the standard resolution. Waiting to see if TCAS activates is not an acceptable substitute for proactive controller separation — TCAS is an emergency backup, not a primary separation tool.
Question 2: Aircraft Alpha is at FL350 heading 090, speed 480 kts. Aircraft Bravo is at FL350 heading 270, speed 460 kts. They are on reciprocal headings 30 NM apart. The closure rate is approximately:
- 940 kts — because reciprocal heading aircraft add their speeds together (Correct answer)
- 480 kts — only the faster aircraft's speed counts for closure
- 20 kts — only the speed difference between the two aircraft matters
- 460 kts — both aircraft are moving so only relative speed above the slower one matters
Correct answer: 940 kts — because reciprocal heading aircraft add their speeds together
On converging reciprocal headings, closure rate is the sum of both aircraft's groundspeeds: 480 + 460 = 940 kts.
When two aircraft are on opposite headings (reciprocal tracks), they are closing toward each other, so both contribute their full speed to the closure rate. At 940 kts closure, 30 NM apart, time to conflict is approximately 30/940 × 60 ≈ 1.9 minutes. This is an extremely short window for controller action. Controllers must recognise head-on traffic scenarios and act early — high closure rate situations are among the most time-critical in radar conflict management.
Question 3: An STCA alert activates for two aircraft at FL280 and FL290 converging from the left and right. The controller's first action should be to:
- Assess the geometry on the radar display to determine which resolution (heading or level) will be most effective (Correct answer)
- Immediately issue an instruction to one aircraft before fully assessing the situation
- Acknowledge the STCA and wait to see if the aircraft diverge on their own
- Transfer both aircraft to the next sector to avoid responsibility for the conflict
Correct answer: Assess the geometry on the radar display to determine which resolution (heading or level) will be most effective
Before issuing an instruction, the controller must quickly assess the geometry to choose the most effective resolution — an ill-considered instruction could worsen the conflict.
While urgency demands rapid action, issuing an instruction without a moment of assessment can worsen a conflict. A heading change that turns an aircraft into the other's path, or a level change to an already occupied level, can create a more serious situation. The correct sequence is: (1) recognise the alert, (2) assess geometry (tracks, levels, closure), (3) determine optimal resolution, (4) issue instruction. In practice this takes seconds. FEAST tests whether candidates assess before acting, not just react impulsively to alerts.
Question 4: A level-bust occurs when an aircraft climbs 400 ft above its cleared FL310 to FL314. In the same vicinity, another aircraft is cleared to FL320. The vertical separation is now:
- 600 ft — insufficient; ICAO minimum is 1,000 ft vertical separation (Correct answer)
- 1,400 ft — sufficient because FL320 is 1,000 ft above the original FL310
- 400 ft — only the deviation amount matters for separation calculation
- 900 ft — halfway between the deviation and the cleared level difference
Correct answer: 600 ft — insufficient; ICAO minimum is 1,000 ft vertical separation
FL320 minus actual altitude FL314 = 600 ft. The ICAO minimum vertical separation of 1,000 ft is violated.
Separation is always measured against actual positions, not cleared positions. If aircraft A is at FL314 (400 ft above its FL310 clearance) and aircraft B is at FL320, the actual vertical separation is FL320 - FL314 = 600 ft. The ICAO standard of 1,000 ft vertical separation is not met. This is a separation infringement. Controllers must track actual radar returns, not assume aircraft are at their cleared levels, especially after level assignments are recently issued.
Question 5: Two aircraft are in conflict and the controller issues a heading change to Aircraft 1. Aircraft 1 does not respond. The controller should:
- Immediately re-issue the instruction, confirm read-back, and if no response, consider instructing Aircraft 2 to resolve the conflict (Correct answer)
- Wait for Aircraft 2 to take TCAS avoiding action before issuing further instructions
- Transfer the conflict responsibility to the military controller
- Issue a MAYDAY for both aircraft and hand off to the emergency frequency
Correct answer: Immediately re-issue the instruction, confirm read-back, and if no response, consider instructing Aircraft 2 to resolve the conflict
Lack of response to a safety-critical instruction requires immediate re-issuance; if still no response, the controller must act on the other aircraft to resolve the conflict.
If a separation instruction is not acknowledged within a few seconds, the controller cannot assume compliance. The immediate steps are: (1) re-issue the instruction clearly, possibly with more urgent phrasing, (2) check callsign accuracy, (3) if still no response, issue instruction to the other aircraft — do not wait for TCAS, as TCAS is a last resort. FEAST conflict management scenarios include NORDO (no radio) conditions to test whether candidates apply fallback procedures rather than passively waiting.
Question 6: A controller detects a conflict between two aircraft where a heading change for Aircraft A would resolve the conflict but would take it into a third aircraft's path. The most appropriate action is to:
- Resolve the original conflict using a level change or a coordinated combination of instructions to all three aircraft (Correct answer)
- Issue the heading change to Aircraft A and deal with the resulting new conflict when it develops
- Declare an emergency and hand all three aircraft to the supervisor
- Instruct Aircraft B to change heading to remove it from Aircraft A's path first
Correct answer: Resolve the original conflict using a level change or a coordinated combination of instructions to all three aircraft
When the obvious resolution creates a secondary conflict, a different resolution method (level change) or coordinated instructions must be used to avoid creating new problems.
Conflict resolution in a complex traffic environment requires system-wide thinking. A resolution that fixes one conflict while creating another simply transfers the problem. The controller must: (1) visualise the effect of each possible instruction on all affected aircraft, (2) choose a resolution that clears the original conflict without creating new ones, (3) if needed, issue coordinated instructions to multiple aircraft simultaneously. FEAST advanced radar scenarios test exactly this — whether candidates think ahead to secondary effects or react locally without system-wide awareness.
FEAST Dynamic Radar Conflict Management 2
Two aircraft are converging at FL290 with a projected closest point of approach (CPA) of 3 NM lateral and 0 ft vertical in 4 minutes.
The ICAO minimum radar separation standard in European airspace is 5 NM.
The controller should: